Based on Chapter 20 of the Sai Satcharitra, what was Das Ganu's specific problem with the Ishavasya Upanishad and what was Sai Baba's advice?

According to Chapter 20, Das Ganu was writing a commentary called 'Ishavasya-Bhavartha-Bodhini' to explain the Ishavasya Upanishad in simple language. His problem was that although he translated it word for word, he could not grasp its internal secret or deep meaning, which left his mind without joy. When he took this doubt to Sai Baba in Shirdi, Baba's advice was that the resolution would come from an unexpected source. As the chapter recounts, Baba told him, 'The resolution of this doubt of yours will be done by the maidservant at Kaka’s house when you return there.'